WHO Study Finds Four In Ten Cancer Cases Worldwide Are Preventable

Up to four in ten cancer cases worldwide—around 7.1 million cases—could be prevented through effective public health interventions, according to a new global analysis by the World Health Organization (WHO) and its International Agency for Research on Cancer (IARC).

Released on World Cancer Day on February 4, the findings highlight how modifiable risk factors continue to drive a substantial share of the global cancer burden, even as treatment costs and caseloads rise.

The analysis identifies tobacco use as the single largest preventable cause of cancer, responsible for 15 percent of all new cancer cases globally. In a significant first, the study also estimates that nine cancer-causing infections together account for about 10 percent of cancer cases worldwide. Other major preventable risk factors flagged include alcohol consumption, high body mass index, physical inactivity, air pollution, and exposure to ultraviolet radiation.

Drawing on data from 185 countries and 36 cancer types, the study estimates that 37 percent of all new cancer cases diagnosed in 2022 were linked to preventable causes. Three cancers—lung, stomach, and cervical—accounted for nearly half of all preventable cancer cases among both men and women worldwide, underscoring the scale of missed opportunities for prevention and early intervention.

Lung cancer was found to be primarily associated with smoking and air pollution, while stomach cancer was largely attributable to Helicobacter pylori infection. Cervical cancer, the analysis noted, was overwhelmingly caused by human papillomavirus (HPV), reinforcing the critical role of vaccination and screening in reducing disease burden.

“This is the first global analysis to clearly quantify how much cancer risk is driven by causes we can prevent,” said Dr. Ilbawi, WHO Team Lead for Cancer Control and an author of the study. “By examining patterns across countries and population groups, the findings provide governments and individuals with more precise, evidence-based information to prevent many cancers before they begin.”

The study also draws attention to gender disparities in preventable cancer burden. Men were found to have a substantially higher share of preventable cancers than women, with 45 percent of new cancer cases in men linked to avoidable risk factors, compared with 30 percent in women. Among men, smoking alone accounted for an estimated 23 percent of all new cancer cases, followed by infections at 9 percent and alcohol consumption at 4 percent.

Among women globally, infections emerged as the leading preventable cause, accounting for 11 percent of new cancer cases. Smoking contributed to 6 percent of cases, while high body mass index accounted for 3 percent, reflecting the growing influence of lifestyle-related risk factors alongside infectious causes.

The report urges governments to adopt prevention strategies tailored to local contexts, warning that a one-size-fits-all approach will not suffice. Key measures highlighted include stronger tobacco control policies, regulation of alcohol use, expanded vaccination coverage against cancer-causing infections such as HPV and hepatitis B, improved air quality, safer working environments, and policies that promote healthy diets and physical activity.

The analysis also notes that investing in prevention delivers benefits beyond cancer control. Reducing exposure to preventable risk factors can lower long-term healthcare costs, ease pressure on overstretched health systems, and improve overall population health and productivity. In low- and middle-income countries, where access to timely diagnosis and treatment remains uneven, prevention offers a particularly cost-effective pathway to reducing avoidable deaths.

As countries mark World Cancer Day, the findings serve as a cautionary reminder that medical advances and expanded treatment access alone will not be enough to reverse global cancer trends. Without sustained investment in prevention, early detection, and risk reduction, millions of cancer cases that could be avoided will continue to place a heavy and unnecessary burden on individuals, families, and health systems worldwide, said the WHO report.